Is anyone "originally" from anywhere they live now, really, except maybe East Africa (at some point in time)? Anglo-Saxons came from the continent, "Americans" from Europe, Africa and elsewhere, Native Americans from Asia, etc.
Greeks.
Dorian Greeks migrated into Mycenae in the early Bronze Age.
Yes, very true (and something I like to remind people who like to display ethnic and/or racial pride and talk about "heritage" etc)